Indian summer–A period, in mid- or late autumn, of abnormally warm weather, generally clear skies, sunny but hazy days, and cool nights.

In New England, at least one killing frost and preferably a substantial period of normally cool weather must precede this warm spell in order for it to be considered a true “Indian summer.” It does not occur every year, and in some years there may be two or three Indian summers. The term is most often heard in the northeastern United States, but its usage extends throughout English- speaking countries. It dates back at least to 1778, but its origin is not certain; the most probable suggestions relate it to the way that the American Indians availed themselves of this extra opportunity to increase their winter stores. The comparable period in Europe is termed the Old Wives’ summer, and, poetically, may be referred to as halcyon days. In England, dependent upon dates of occurrence, such a period may be called St. Martin’s summer, St. Luke’s summer, and formerly All-hallown summer.

According to AMS we can’t call “Indian Summer” in the metro anytime soon for 3 reasons:

1) We haven’t had a frost in most of the metro yet. While we have seen frost and a hard freeze in much of Minnesota, the inner core of the metro is still frost free…and the growing season continues.

2) It’s not “mid to late autumn.” Fall began Saturday at 9:49am. It was actually still summer on Saturday morning…just 3 days ago. The AMS definition of “mid-to late autumn” implies at least the second half of October, or early November for true “Indian Summer.”

3) It’s not “abnormally mild.” With the average high still at 67 this week, it’s not at all unusual to see temps in the 70s in late September. So right now the forecast doesn’t look “abnormally mild” either.

We may still get a glorious Indian Summer this year…but we’ll have to wait for frost in the metro and then warm weather in mid-late October or early November. Declaring it sooner is pushing the season.

Image Credit: Bill Stein

Metro Colors: Best in show for 2012?

We’re getting reports from the MN DNR and photos that suggest some of the most vivid fall color this year in Minnesota seem to be centered on parts of the Twin Cities metro.

Source: MN DNR

What could be causing the metro show?

Source: MN DNR

2012 may be the “perfect color storm” in the Twin Cities.

We saw heavy rainfall at the beginning of the growing season as the trees leafed out in late April and May this year. That meant plenty of moisture for trees to produce excellent and healthy foliage.

As drought set in during late summer, that may have provided additional “stress” to metro trees at just the right time to induce a blaze of color.

Trees in southern & western Minnesota battled drought all year, and may be too stressed to put on the best color show.

Leaf peepers in the metro may be treated to some of the best fall color shows in Minnesota over the next 2-3 weeks.

About the blogger

Paul Huttner is chief meteorologist for Minnesota Public Radio. Huttner has worked TV and radio stations in Minneapolis, Tucson and Chicago. Paul is a graduate of Macalester College in St. Paul and holds a bachelor’s degree in geography with an emphasis in meteorology.